1. Field of the Invention
The present invention relates to an image forming apparatus connectable to a network.
2. Description of the Background Art
A portable, handy image forming apparatus has been known as an image forming apparatus enabling on-site printing of image data saved in a portable terminal such as a note type PC, a digital still camera and the like. Japanese Patent Laying-Open No. 2002-205421 (hereinafter referred to as '421 Reference) discloses such a portable image forming apparatus (print control device). A portable image forming apparatus generally uses a battery as a power source. Therefore, such an apparatus has a problem that if the power supplied from the power source runs short during printing, printing abruptly stops. In order to avoid such a trouble, the print control device of '421 Reference skips printing of a color material layer and an overcoat layer, if it is determined that remaining amount of power is low during printing.
Recently, as one type of information processing apparatuses, an image forming apparatus (typically a copy machine) has been introduced to many places of business (companies and offices). In such a place of business, it is becoming a common practice to have an image forming apparatus having a printer function or copy function connected to a network and to share the apparatus by a plurality of users. Further, image forming apparatuses having a plurality of operational modes including a copy mode, an image communication mode (typically a facsimile mode), a network compatible printer mode and a scanner mode, such as an MFP (MultiFunction Peripheral), are increasing in number.
Different from the portable image forming apparatus or a portable terminal such as a note type PC provided with a battery, the image forming apparatus of this type is fed by mains power and, hence, free from low battery problems. In Japan, mains power supply has been very stable, except for very few accidental outages. Therefore, it has been a matter-of-course that power is always supplied stably to an image forming apparatus, and it has been unnecessary to consider any special measure to cope with low battery, or to prepare for expected power outage time.
Considering electricity supply situations of late, however, the stable power supply that has been long taken for granted (guaranteed) may no longer be realistic. Interruption of power supply or sudden blackout could occur at any time. Therefore, there has been a demand for managing and controlling image forming apparatuses with limited power supply. As a method for reducing power consumption, the energy-saving technique of '421 Reference may be applied to an image forming apparatus such as the MFP.
According to the technique of '421 Reference, however, though the power consumed for one printing operation can be saved as part of the printing process is omitted, the effect of saving power consumption is relatively small when the number of printing increases. Particularly when the image forming apparatus is shared by a plurality of users, many jobs may be handled at one time and, hence, if many jobs are executed at a time zone when electricity use peaks, the maximum power consumption would be so high as to cause power shortage. The technique described in '421 Reference cannot avoid such a situation.